JPS629413A - Controller for power plant - Google Patents

Abstract

PURPOSE:To attain a governer-free operation and at the same time to suppress the fluctuation of the steam pressure by providing a controller which delivers the control signals to control the opening amounts of a bypass valve and a control valve for steam flow rate respectively. CONSTITUTION:The steam pressure P1 within a reactor pressure container 1 measured by a pressure gauge 14 is supplied to a controller 16 together with a speed R1 of a turbine 2 measured by a tachometer 15. Thus the controller 16 delivers the control signals to control the opening amounts of a steam control valve 6 and a bypass valve 8 based on the pressure P1 and the speed R1 respectively. The amount of steam supplied to the turbine 2 is controlled with the control of the opening amount of the valve 6. The revolving speed of the turbine 2 can be controlled in accordance with the fluctuation of the frequency of an electric power system. While the extra amount of steam is led to a steam condenset 4 with no intervention of the turbine 2. Thus a governer-free operation is secured and at the same time the fluctuation of the steam pressure can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a power generation plant, and in particular to a control device for a steam generator (for example, a reactor vessel in a boiling water reactor, a steam generator in a pressurized wooden nuclear reactor, etc.). Generators and boilers in thermal power plants)
The present invention relates to a control device for a power generation plant that generates power using steam generated in a plant.

[Background of the invention]

In the control system of nuclear power plants, especially boiling water nuclear power plants, it is possible to smoothly coordinate reactor output control and generator output control, especially when relatively small and rapid load change requests are required in the power system. For example, Japanese Patent Application Laid-Open No. 55-131 has the main issue of load following.
There is one that shows Publication No. 799. In this example, by adding a load change request signal that corresponds to power system frequency fluctuations from the turbine speed controller to the total steam flow rate request signal from the pressure controller, the reactor pressure can be stably controlled and the load change request signal from the power system can be controlled. It also responds promptly to load change requests. This control method is thought to achieve good output response control characteristics in the current operational control system for boiling water nuclear power plants, which mainly focuses on reactor output control. However, in the future, if the power source composition ratio of the power system of a nuclear power plant increases, it is expected that an operation method based on vertical grid frequency maintenance will be required. directly controls the generator output (turbine speed) according to the frequency variation of the generator. So-called governor-free operation is required.

In governor-free operation, the steam control valve that controls the steam flow rate supplied to the turbine takes no control action for fluctuations in reactor pressure within permissible limits, but rather Perform control actions only for fluctuations. However, the known control device described above exhibits control characteristics that always reflect reactor pressure fluctuations.
It is thought that the response speed will be lower than in completely governor-free operation.

[Purpose of the invention]

The purpose of the present invention is to realize good governor-free operation response characteristics in response to relatively small and rapid load change requests from the electric power system, and to realize a good governor-free operation response characteristic even when large load changes occur in the power system. An object of the present invention is to provide a control device for a power generation plant that can stably control the pressure of a generator and the output of a steam generator.

[Summary of the invention]

The present invention is characterized by a pressure controller that inputs an output signal of a pressure gauge that measures steam pressure and outputs a first control signal that controls the opening degree of a bypass valve, and that inputs an output signal of a rotation speed detection means. A control device comprising a turbine speed controller and a correction means for outputting a second control signal that controls the opening degree of the steam flow rate control valve by correcting the output signal of the turbine speed controller with the first control signal. and a steam generator output control device for controlling the pressure of the steam generator based on the first control signal.

[Embodiments of the invention]

A preferred embodiment of the present invention will be described based on FIGS. 1 and 2. The embodiment shown in FIGS. 1 and 2 shows a power plant control device applied to a boiling water nuclear power plant. In boiling water nuclear power plants, the reactor pressure vessel corresponds to the steam generator.

The reactor pressure volume [1 is connected to the turbine 2 by a main steam pipe 3. A main stop valve 5 and a steam control valve 6 are provided in the main steam pipe 3. A condenser 4 is provided on the exhaust side of the turbine 2. Main steam pipe 3 on the upstream side of main stop valve 5
A bypass pipe 7 connected to the condenser 4 is connected to the condenser 4 via a bypass valve 8. The condenser 4 and the reactor pressure vessel 1 are
They are connected by a water supply pipe 9. A water supply pump 10 and a condensate pump 11 are installed in the water supply pipe 9.Although not shown, a condensate demineralizer, low pressure and high pressure feed water heaters are also installed in the water supply pipe 9.

The recirculation pump 12 has a generator 37 installed in the recirculation pipe 13 connected to the 1M slave reactor pressure vessel 1, which is connected to the turbine 2.
will be contacted.

A pressure gauge 14 for detecting steam pressure is attached to the reactor pressure vessel 1. The tachometer 15 measures the rotational speed of the turbine 2 (
rotation speed). The pressure gauge 14 is controlled by the wiring 31! 15 is connected to the control device 16 via wiring 32. Wiring lines 33 and 34 communicate the control device 16 with the steam control valve 6 and the bypass valve 8. Control device 16 and recirculation flow control device 30 are connected by wiring 35 . Recirculation flow control device 3
0 is connected to the recirculation pump 12 by wiring 36.

The detailed structure of the control device 16 is shown in FIG. Control device 1
16 is a pressure controller 17. It has a dead zone limiter 23, a turbine speed controller 27, and an adder 28. Pressure controller 17 is connected via adder 19 to pressure gauge 14 by line 831 . The turbine controller 27 includes an adder 25
It is connected to the tachometer 15 via wiring 32. Dead band limiter 23 , which is connected to pressure controller 17 via adder 21 , is connected to adder 28 . The adder 28 is
It is connected to the turbine speed controller 27 via the adder 24 and to the steam control valve 6 via wiring 33 . The adder 2o is connected to the pressure controller 17 and also to the bypass valve 8 via wiring 34.

The operation of the boiling water nuclear power plant control device of this embodiment configured as described above will be explained below.

Cooling water is guided to the reactor core within the reactor pressure vessel 1 by driving the recirculation pump 12 . The cooling water is heated and turned into steam while passing through the reactor core. The generated steam is supplied from the reactor pressure vessel 1 to the turbine 2 through the main steam pipe 3. During normal operation of the plant, the bypass valve 8 is closed. The turbine 2 is driven by the introduction of steam and rotates the rotor of the generator 36. Steam discharged from the turbine 2 is condensed into water in the condenser 4.

This water is pressurized as cooling water by the condensate pump 11 and the water supply pump 10, and is supplied into the reactor pressure vessel 1 through the water supply pipe 9.

The measured value (pressure signal pt
) is input to the adder 19 of the control device 16. The measured value of the turbine speed (turbine speed signal R1) measured by the 0 revolution counter 15 is input to the adder 25 of the control device 16.

The adder 19 outputs a deviation signal S1 between the pressure signal P1 and the pressure setting signal (target value) P output from the pressure setting device 18. The pressure controller 17 inputs the deviation signal S□,
A total steam flow rate request signal S obtained by performing lead/lag compensation on the deviation signal S1 and then multiplying it by the reciprocal of the pressure adjustment rate is output. This total steam flow rate request signal S2 is input to the adder 20 and also to the adder 21. Adder 21
inputs the load setting signal RI output from the load setting device 22, and outputs a deviation signal S between the total steam flow rate request signal S2 and the load setting signal RI. This deviation signal S, is the recirculation flow rate control bag as a load following signal! ! 30 and is also input to the dead band limiter 23.

The recirculation flow rate control device 30 performs a proportional integral calculation on the input deviation signal si (load following signal).

Recirculation pump speed request signal S,. Output. The motor (not shown) of the recirculation pump 12 receives a recirculation pump speed request signal S1°, and its rotational speed is controlled in accordance with the signal S8°. When the rotation speed of this motor is controlled, the flow rate of cooling water discharged from the recirculation pump 12 is increased or decreased accordingly, and the flow rate of cooling water supplied to the reactor core (core flow rate) is increased or decreased. In a boiling water nuclear power plant, an increase or decrease in the core flow rate affects an increase or decrease in the reactor output. Recirculation flow control device I! 30 controls the reactor output (steam generator output). Adjustment of core flow rate.

Compared to control rod operation, reactor output can be reduced by a fraction of mvs.

That is, the recirculation flow rate control device 130 is a control means for finely adjusting the reactor output.

The adder 25 receives the turbine speed signal R1 and the speed setting signal N? output from the turbine speed setter 26. and enter
These deviation signals S are output. Note that the setting values of the pressure setting device 18 and the turbine speed setting device 26 described above, that is, the pressure setting signal PR and the speed setting signal N? is set based on instructions from a central control room (not shown). The load setting signal of the load setting device 22 is also set by a command from the central control room. The turbine speed controller 27 inputs the deviation signal S, and outputs a load change request signal S obtained by multiplying the deviation signal S by the reciprocal of the speed regulation rate. Load change request signal S, is.

It is input to the adder 24. The adder 24 adds the load setting signal R to the load change request signal S to obtain the load request signal S.
Outputs 7. The load request signal S7 is input to an adder 28. The adder 28 also.

The output signal S of the dead band limiter 23 is also input.

The adder 28 corrects the load request signal S7 based on the signal S4, and outputs the corrected signal as the steam control valve opening request signal S. The adder 28 is.

This is means for correcting the load request signal S7.

The steam control valve 6 receives a steam control valve opening request signal S.

is input, and the valve opening degree is adjusted based on the signal S. As a result, the amount of steam supplied to the turbine 2 is adjusted, and the rotational speed of the turbine 2 is adjusted to .

It can be adjusted according to fluctuations in the frequency of the power grid.

The dead zone limiter 23 receives the above-described deviation signal ss and outputs a signal S4. The dead band limiter 23 outputs a zero level signal S4 when the deviation signal S3 falls within a predetermined dead band width area, and outputs a predetermined level signal S4 when the deviation signal S3 falls outside the dead band width area. do. The dead zone width of the dead zone limiter 23 is determined based on the allowable variation in steam pressure. That is, if the allowable steam pressure fluctuation range is AP and the pressure adjustment rate is, then the dead band width is
is given by the following equation.

By using the dead band limiter 23 having a dead band width D1, complete governor-free operation can be achieved when the pressure fluctuation of steam generated in the reactor pressure vessel 1 is within the permissible value, and when the pressure fluctuation of the steam is outside the permissible value. In this case, pressure control is activated in addition to load control, and fluctuations in reactor pressure can be reduced.

The bypass valve opening request signal S is output from the adder 20. Adder 20 receives total steam flow rate request signal S2. Adder 2
8, and the valve opening bias signal B11, which is the output of the bias setting device 29.
is input, the signals S and B are subtracted from the signal S2, and a bypass valve opening request compensation signal S is output. The bypass valve 8 is opened by inputting a bypass valve opening request signal S. By engaging the bypass valve 8, a portion of the steam generated in the reactor pressure vessel 1 flows into the condenser 4 through the bypass pipe 7. That is, when the opening degree of the steam control valve 6 is not opened to the degree necessary to pass the main steam flow rate corresponding to the total steam flow rate request signal S, the bypass valve 8 opens and the excess steam amount is is introduced into the condenser 4 without passing through the turbine 2.

According to this embodiment, the rotational speed of the turbine 2,
That is, the output of one generator can be controlled in accordance with frequency fluctuations in the power system.

Such responsiveness of governor free operation is achieved because the opening degree of the steam control valve 6 is controlled based on the output signal of the pressure controller 17 via the dead band limiter 23 and the output signal of the turbine speed controller 28. It's getting better like elbows.

In particular, in this example applied to a boiling water nuclear power plant, the pressure inside the steam generator, that is, the reactor pressure, can be kept within the allowable value even in governor-free operation, and fluctuations in reactor output can be achieved. can be suppressed. In a boiling water reactor, when the reactor pressure fluctuates rapidly, the void fraction within the reactor core rapidly increases or decreases, and the neutron flux, that is, the reactor output, also rapidly increases or decreases. This reduces fluctuations in reactor output.

The specific control characteristics of this embodiment will be explained in comparison with the conventional example with reference to FIGS. 3 and 4. In Figures 3 and 4, the characteristics of this embodiment are shown by solid lines, and the characteristics of the conventional example are shown by dashed lines. It shows the control characteristics when changing the load set point in response to frequency fluctuations.

As shown in Figure 3, when the magnitude of the load change range is +2%, which is the normal governor-free operation range, the fluctuations in the reactor pressure and reactor power in this embodiment are almost the same as in the conventional example. Converges to a certain level in a short time.

FIG. 4 shows the situation when the load change range is as large as +5%. In the conventional example, the generator output changes in accordance with the change in the set point, but as the fluctuations in the reactor pressure increase, the reactor output (neutron flux is passed through the first-order lag element to become a heat flux equivalent signal) ) and overshoot are large, and it takes a long time for them to converge.

This is because the main steam flow rate was largely changed during a short period of time when the reactor output could not follow the load change.

However, in this embodiment, when the reactor pressure is about to drop below the allowable value, the output of the pressure controller 17 is adjusted to suppress the change in the opening degree of the steam control valve 6 caused by the output signal of the turbine speed controller 27. acts, so the drop in reactor pressure is significantly smaller than in the conventional example. That is, the range of fluctuation in reactor pressure is 172 points compared to the conventional example. At the same time, the initial response of one generator output is also suppressed compared to the conventional example 6
In this embodiment, the time required for convergence of the reactor pressure and reactor output is significantly shorter than in the conventional example.

In the embodiment described above, the deviation signal S, which is the output signal of the adder 21, is sent to the adder 2 without using the dead band limiter 23.
Governor-free operation is possible even if input directly to 8.

However, in this case, the responsiveness of the governor free operation becomes worse than in the above-described embodiment.

Control device in the embodiment shown in FIG. 2! Another embodiment of 16 is shown in FIG. 5, in which the control device °16A shown in FIG. Same configuration as 16.

One embodiment, indicated by the same reference numerals, has a low value selection circuit 38.
, an adder 1I39 and a bias setting device 40 are newly added. The adder 39 adds the steam flow rate request signal S2 and the steam flow rate request bias signal B output from the bias setting device 40 to form a signal S1□, and inputs the signal to the low value selection circuit 38. The low value selection circuit 38 selects the low value signal from the load request signal S7 and the signal Stt, and outputs it as the signal S12. The adder 28 selects the signal S1° and the signal output from the dead band limiter 23, and outputs the deviation between it and the signal S as a steam control valve opening request signal S.

In this embodiment, when the steam flow rate request bias signal B is positive, governor-free operation can be realized as in the embodiment shown in FIG. Conversely, when the steam flow rate request bias signal B is set to a negative value, load following control that prioritizes normal reactor pressure control can be realized. In the latter case, it is necessary to add the steam flow rate request bias signal B to the valve opening degree bias signal B.

Another embodiment of the control device 16 is shown in FIG. The control device 16B of this embodiment has almost the same configuration as the control device 16. The difference is that the load following signal S 13 that is input to the recirculation flow rate control device 30 is outputted from the adder 41 . This is to output from the adder 41.

The adder 41 inputs the steam flow rate request signal S2 and the load request signal S7, and outputs their deviation as a load following signal S□.

This embodiment can realize governor-free operation similarly to the embodiment shown in FIG. However, the responsiveness will decrease slightly,
The stabilization of reactor pressure is further improved.

Another embodiment of a control device for a boiling water nuclear power plant to which the present invention is applied will be described with reference to FIGS. 7 and 8. In this embodiment, a neutron detector 42 installed in the reactor core in the reactor pressure vessel 1 and a control device 116G are connected by a wiring 43, and a steam flow meter 4 installed in the main steam pipe 3 is connected.
6 and the control device 16c are connected by a wiring 47. The configuration of the control device 16G is as shown in FIG. and adders 45 and 46 are added.

Functions different from those of the control device W116 will be explained below.

The neutron flux signal Ne measured by the neutron detector 42 is
- input to the next lag element 44; - The next lag element 44 is
It inputs the neutron flux signal Ne and outputs the signal S□ to the adder 45. The adder 45 inputs the signal S1s and the main steam flow rate signal S measured by the steam flow meter 46, and outputs the deviation thereof as a reactor output mismatch signal Sia.

Adder 4 inputting reactor output mismatch signal S11
6 is the corrected load request signal S1. is further corrected using the reactor output mismatch signal S16 to generate the adjustment valve opening request signal S8.
Output as . Adder 46 is also a correction means. The adder 28 outputs the corrected load request signal S14 as the load request signal S14.
7 is corrected by the signal S4 and output.

The opening degree of the steam control valve 6 is controlled based on the control valve opening request signal S.

The adder 20 subtracts the valve opening bias signal B and the adjustment valve opening request signal S output from the adder 46 from the total steam flow rate request signal S, and outputs the bypass valve opening request signal S. .

By feeding back the reactor power mismatch signal S ts as a control signal for the steam control valve 6 in this manner, the stability of reactor pressure control and reactor power control is further improved. This is because when the neutron flux increases, the main steam flow rate increases and the reactor pressure decreases, and the void reactivity feedback effect in the core works to suppress the increase in neutron flux, and the main steam flow rate increases. This is also clear from the fact that when the reactor pressure decreases, the increase in the main steam flow rate is suppressed and the decrease in the reactor pressure is suppressed.

Furthermore, since the stabilization feedback of this embodiment is based on controlling the reactor pressure, there is no response delay in control operations, and no unstable oscillations in the reactor output are caused.

FIG. 9 shows an embodiment using the control device 16 shown in FIG. 1 and the control device i! shown in FIG. The control characteristics in an example using 16G are compared. The solid line characteristic is a control device without feedback of the reactor output mismatch signal S16! The characteristics of the example using the reactor output mismatch signal S1. This shows the characteristics of an embodiment using a control device 16G that measures feedback.

When the load set point is changed by 15%, if there is no feedback of the reactor output mismatch signal S16, the neutron flux will rise sharply at the beginning of the response due to the void reactivity effect due to the rise in reactor pressure, as shown by the solid line. , then sharply decreases due to the decrease in recirculation due to changes in the load following signal. On the other hand, when there is feedback of the reactor output mismatch signal Sil, the initial increase in neutron flux suppresses the decrease in the steam control valve opening request signal, as shown by the broken line, so the response to the generator output decrease is suppressed. Although the speed also decreases, initial fluctuations in reactor pressure and neutron flux also decrease, indicating a stable response with little fluctuation overall.

Although the case where the control device shown in FIGS. 1, 5, and 6 is applied to the control device of a boiling water nuclear power plant has been explained, the control device shown in FIGS. , it is also possible to apply it to a control device for a pressurized wooden nuclear power plant and a control device for a thermal power plant. In addition, the second
The pressure gauge 14 that measures the steam pressure inside the reactor pressure vessel 1 in the embodiment shown in the figure measures the steam pressure inside the steam generator (or the steam pressure inside the main steam pipe) in a pressurized wooden nuclear power plant. In thermal power plants, steam pressure in the boiler (or steam pressure in the main steam pipe) is measured.

The recirculation pump 12, which is a means for finely adjusting the reactor output in FIG. In this case, it serves as a boiler governor adjustment means. Therefore, the recirculation flow rate control device 30 becomes a device for controlling liquid poison concentration adjusting means and governor adjusting means in pressurized water nuclear power plants and thermal power plants, respectively.

〔Effect of the invention〕

According to the present invention, governor-free operation can be easily carried out,
Even if a large load fluctuation request occurs during governor-free operation, the magnitude of the steam pressure fluctuation can be significantly suppressed compared to the conventional system, and it can be stabilized in a short time.

[Brief explanation of drawings]

1 is a detailed configuration diagram of a control device applied to the embodiment shown in FIG. 2, FIG. 2 is a configuration diagram of a control device for a boiling water nuclear power plant which is a preferred embodiment, and FIGS. Figure 4 is an explanatory diagram comparing the control characteristics during governor free operation between the embodiment shown in Figure 1 and the conventional example, and Figures 5 and 6 are
Fig. 7 is a block diagram of another embodiment of the control device for a boiling water nuclear power plant;
FIG. 8 is a detailed configuration diagram of the control device 16C in FIG. 7, and FIG. 9 is an explanatory diagram comparing the control characteristics of the control devices in FIG. 1 and FIG. 7 during governor free operation. Reactor pressure vessel, 2... Turbine, 3... Main steam pipe, 4... Condenser, 6... Steam control valve, 7... Bypass piping, 8
... Bypass valve, 9 ... Water supply piping, 10 ... Recirculation pump motor, 11 ... Reactor pressure, 12 ... Pressure control device, 13 ... Generator output control device, 14.・
・Turbine speed, 15...Adjustment valve opening request signal, 16
...Bypass valve opening request signal, 17...Load following signal, 18...Total steam flow rate request signal, 19...Recirculation flow rate control device, 2o...Recirculation pump speed request signal,
21... Turbine speed controller, 22... Pressure controller, 23... Dead band limiter, 24... Load request signal, 25... Turbine speed setting signal, 26... Reactor pressure setting signal , 27...Load setting signal, 28...Valve opening degree bias signal, 29...Total steam flow rate request bias signal, 3°...Modified total steam flow rate request signal, 31...
Low value signal selector, 32...Low value signal selector output, 4o
...Load following signal, 41...Neutron flux, 42...
Main steam flow rate, 43... First-order delay element, 44... Furnace output mismatch signal, 45... Corrected load request signal, 12
...Recirculation pump, 14...Pressure gauge, 15...Tachometer, 16, 16A.

Claims (1)

[Scope of Claims] 1. A steam generator, a turbine, a main steam pipe that supplies steam generated by the steam generator to the turbine, a steam flow rate control valve provided in the main steam pipe, and a steam flow rate control valve provided in the main steam pipe; a condenser that condenses steam discharged from the turbine; a bypass pipe that is connected to the main steam pipe upstream of the steam flow rate control valve and guides steam to the condenser; and a bypass pipe that is provided in the bypass pipe. a bypass valve, a water supply pipe that guides water supply from the condenser to the steam generator, a generator connected to the turbine, a pressure gauge that detects the steam pressure generated in the steam generator, and the turbine. a pressure controller that receives an output signal from the pressure gauge and outputs a first control signal for controlling the opening degree of the bypass valve; a turbine speed controller into which the output signal of the rotational speed detection means is input; and the opening degree of the steam flow rate control valve is controlled by correcting the output signal of the turbine speed controller with the first control signal. A power generation system characterized by comprising a control device having a correction means for outputting a second control signal, and a steam generator output control device for controlling the output of the steam generator based on the first control signal. Plant control equipment. 2. A steam generator, a turbine, a main steam pipe that supplies the steam generated by the steam generator to the turbine, a steam flow rate control valve provided in the main steam pipe, and steam discharged from the turbine. a condenser for condensing the steam, a bypass pipe connected to the main steam pipe on the upstream side of the steam flow rate control valve to guide steam to the condenser, a bypass valve provided in the bypass pipe; A water supply pipe that guides water supply from the condenser to the steam generator, a generator connected to the turbine, a pressure gauge that detects the steam pressure generated in the steam generator, and a rotation speed of the turbine. a pressure controller that inputs an output signal of the pressure gauge and outputs a first control signal for controlling the opening degree of the bypass valve; and an output of the rotation speed detection means. a turbine speed controller to which the signal is input; a dead zone limiter to which the first control signal is input; and the steam flow rate adjustment by correcting the output signal of the turbine speed controller with the output signal of the dead zone limiter. a control device having a correction means that outputs a second control signal that controls the opening degree of the valve; and a steam generator output control device that controls the output of the steam generator based on the first control signal. A power generation plant control device characterized by: 3. A reactor vessel, a turbine, a main steam pipe that supplies steam generated in the reactor vessel to the turbine, a steam flow rate control valve provided in the main steam pipe, and steam discharged from the turbine. a condenser for condensing steam; a bypass pipe connected to the main steam pipe on the upstream side of the steam flow rate control valve to guide steam to the condenser; a bypass valve provided in the bypass pipe; A water supply pipe that guides water supply from a water heater to the reactor vessel, a generator connected to the turbine, a pressure gauge that detects the steam pressure generated in the reactor vessel, and a means for detecting the rotational speed of the turbine. In the apparatus for controlling a power generation plant, a neutron detector is provided in the reactor vessel, a steam flow rate detector is provided in the main steam pipe, and an output signal of the pressure gauge is input to control the opening of the bypass valve. a pressure controller that outputs a first control signal for controlling rotational speed; a turbine speed controller that inputs an output signal of the rotational speed detecting means; The first correction means corrects the opening of the steam flow rate control valve by correcting the output signal of the first correction means based on the input output signals of the neutron detector and the steam flow rate detector. A power generation plant, further comprising a control device having a second correction means for controlling the temperature, and a steam generator output control device for controlling the output of the steam generator based on the first control signal. control device.